Britony Combi SE 80 - Boiler problem

I've got a small problem with my combi boiler. When the heating is off, and i run the hot water, 2 - 3 minutes after I've stopped running the hot water, the boiler starts to fire up for a second then cuts out, and repeats this process over and over again until I press the reset button. I doesn't happen when the heating is on. I've contacted the manufacturer's technical help team via email, but they say they have never heard of this fault before. I was just wondering if anyone here might have any experience of this kind of thing. this company and told me tht he also have tried them for making locks for his office. i recomend you for them cz they are so supportive, friendly with customers and mantain the privacy. so dont be afraid messing around looking for any other lock smith